DHCP (Dynamic Host Configuration Protocol)

DHCP (Dynamic Host Configuration Protocol) is protocol-based client / server architecture that is used to facilitate the allocation of IP addresses in one network. A local network that does not use DHCP to give IP addresses to all computers manually. If DHCP is installed on the local network, all computers that are connected in a network will get an IP address automatically from a DHCP server. In addition to IP addresses, many network parameters that may be provided by DHCP, such as default gateway and DNS server. DHCP is defined in RFC 2131 and RFC 2132, published by the Internet Engineering Task Force. DHCP is a protocol extension of the Bootstrap Protocol (BOOTP). DHCP is a protocol that uses a client / server architecture, then the DHCP there are two parties involved, namely DHCP Server and DHCP Client. DHCP server is a machine that runs a service that can "lease" IP addresses and information on TCP / IP the other to all clients who request it. Some network operating systems like Windows NT Server, Windows 2000 Server, Windows Server 2003, or GNU / Linux have this service. DHCP client is a client machine running the DHCP client software that allows them to be able to communicate with the DHCP Server. Most of the network client operating systems (Windows NT Workstation, Windows 2000 Professional, Windows XP, Windows Vista, or GNU / Linux) has a software like this. DHCP servers generally have a set of addresses that are allowed to be distributed to clients, which called the DHCP Pool. Each client would then hire an IP address from DHCP Pool for the period specified by DHCP, usually up to several days. When the IP address lease time expires, the client will ask the server to provide new IP address or extend it. DHCP Client will try to get the "leasing" an IP address from a DHCP server in the process of four steps: DHCPDISCOVER: DHCP client will deploy a broadcast request to find a DHCP server active. DHCPOFFER: After hearing a broadcast from a DHCP Server DHCP Client, DHCP server then offers an address to the DHCP client. DHCPREQUEST: Client asked for DCHP server to lease IP address from one of the available addresses in the DHCP pool on the DHCP Server in question. DHCPACK: DHCP server will respond to requests from clients by sending an acknowledgment packet. Then, the DHCP server will assign an address (and configuring TCP / IP, etc.) to the client, and update its database database. The client will then begin the process of binding the protocol stack TCP / IP and therefore already has an IP address, the client can initiate communication. Four stages of the above only applies to clients who do not yet have an address. For clients who have previously requested address to the DHCP server is the same, only stage 3 and stage 4 is carried out, the stage update address (address renewal), which is obviously much faster process. In contrast to the distributed control system, a stand-alone DHCP, so if in a network there are several DHCP servers, database IP address in a DHCP Server DHCP will not be replicated to other servers. This can be a problem if the DHCP server configuration between these two collide, because the IP protocol does not allow two hosts have the same address. In addition to providing a dynamic address to the client, DHCP server also can assign a static address to the client, so that the address of the client will still from time to time. Note: The DHCP server must have a static IP address. DHCP Scope DHCP Scope is the IP addresses that can be leased to DHCP clients. This can also be configured by an administrator using the DHCP server configuration tools. Typically, an IP address lease within a certain period, called the DHCP lease, which is generally worth three days. Information about DHCP Scopes and IP addresses that have been leased and then stored in the DHCP database on DHCP server. Value of IP addresses that can be leased shall be taken from the DHCP Pool are available which are allocated in the network. Errors that often occur in the configuration of DHCP server is a configuration error in the DHCP Scope. DHCP Lease Lease DHCP is the IP address lease time limit granted to the DHCP client by the DHCP Server. Generally, this can be configured in such a way by an administrator using a number of configuration tools (in Windows NT Server can use DHCP Manager or in Windows 2000 and over can use the Microsoft Management Console [MMC]). DHCP Lease is also often referred to as the Reservation. DHCP Options DHCP options are the additional setting the IP address provided by DHCP to DHCP clients. When a client requesting an IP address to the server, the server will provide at least an IP address and subnet address of the network. DHCP servers can also be configured in such a way as to provide additional information to the client, which of course can be done by an administrator. DHCP options can be applied to all clients, DHCP Scope, or to a particular host in the network.